The present invention relates to electrostatically actuatable light modulators for spatially modulating incident light to produce images dependent upon the applied controlling electrical signals. The most common technology employed for television and other similar graphics display applications is the well known cathode ray tube. This well-developed scanning electron beam and light emitting phosphor technology has the disadvantages, however, of requiring rather high voltages and large evacuated glass enclosures and of being relatively expensive to manufacture.
A second display technology gaining importance, especially in smaller display applications, is the liquid crystal display. This display requires low driving voltages and operates in either a reflective or transmissive mode to modulate the incident light. A flat panel construction makes it attractive for small physical volume applications. It has a rather limited color capability, however, and is somewhat temperature sensitive. The ability to produce large arrays with individually addressable pixels, moreover, is a serious manufacturing challenge.
Some of these disadvantages have been addressed in more recent inventions of H. C. Nathanson disclosed in U.S. Pat. No. 3,746,911 entitled, "Electrostatically Deflectable Light Valves For Projection Displays", of L. J. Hornbeck disclosed in U.S. Pat. No. 4,441,791 entitled, "Deformable Mirror Light Modulator", and of G. E. Ott disclosed in U.S. Pat. No. 4,680,579 entitled, "Optical System For Projection Display Using Spatial Light Modulator System". These inventions utilize the semiconductor processing technology to effect the fabrication of high density pixel structures on silicon. The advantages of low cost batch processing techniques, therefore, accrue to these inventions but these advantages are offset by the requirement for concomitant complicated auxiliary elements; in the case of Nathanson, an electron beam tube and in the case of Ott, incorporating the modulator of Hornbeck, a Schlieren optical system.